Sung Uk Kuh

The electron beam deposition of titanium on polyetheretherketone (PEEK) and the resulting enhanced biological properties

The surface of polyetheretherketone (PEEK) was coated with a pure titanium (Ti) layer using an electron beam (e-beam) deposition method in order to enhance its biocompatibility and adhesion to bone tissue. The e-beam deposition method was a low-temperature coating process that formed a dense, uniform and well crystallized Ti layer without deteriorating the characteristics of the PEEK implant. The Ti coating layer strongly adhered to the substrate and remarkably enhanced its wettability. The Ti-coated samples were evaluated in terms of their in vitro cellular behaviors and in vivo osteointegration, and the results were compared to a pure PEEK substrate. The level of proliferation of the cells (MC3T3-E1) was measured using a methoxyphenyl tetrazolium salt (MTS) assay and more than doubled after the Ti coating. The differentiation level of cells was measured using the alkaline phosphatase (ALP) assay and also doubled. Furthermore, the in vivo animal tests showed that the Ti-coated PEEK implants had a much higher bone-in-contact (BIC) ratio than the pure PEEK implants. These in vitro and in vivo results suggested that the e-beam deposited Ti coating significantly improved the potential of PEEK for hard tissue applications.

Contributing factors affecting the prognosis surgical outcome for thoracic OLF

The thoracic ossification of ligamentum flavum (OLF) is a disease that produces spastic paraparesis, and there are various factors that may affect the surgical outcome of thoracic OLF patients. The authors of this study treated 19xa0of these thoracic OLF patients from 1998xa0to 2002, and retrospectively reviewed the patients′ age, sex, symptom duration, involved disease level, preoperative clinical features, neurological findings, radiological findings, the other combined spinal diseases and the surgical outcomes. There were excellent or good surgical outcomes in 16xa0patients, but 3xa0patients did not improve after thoracic OLF surgery: this included 1xa0patient, whose motor function worsened after decompressive thoracic OLF surgery. The favorable contributing factors of surgical outcome in thoracic OLF are a short preoperative symptom duration, single-level lesion, and unilateral lesion type on CT axial scan. On the contrary, the poor prognostic factors are beak type lesion and intramedullary signal changes on T2-weighted sagittal MRI. The complete preoperative evaluation including radiologic findings will provide valuable aid in presuming the surgical outcome for the thoracic OLF patients.

Unilateral versus bilateral percutaneous pedicle screw fixation in minimally invasive transforaminal lumbar interbody fusion

OBJECTnClinical results for unilateral pedicle screw fixation after lumbar interbody fusion have been reported to be as good as those for bilateral instrumentation. However, no studies have directly compared unilateral and bilateral percutaneous pedicle screw fixation after minimally invasive surgery (MIS) for transforaminal lumbar interbody fusion (TLIF). The purpose of this study was to determine whether unilateral percutaneous pedicle screw fixation is comparable with bilateral percutaneous pedicle screw fixation in 1-segment MIS TLIF.nnnMETHODSnThis was a prospective randomized study of 53 patients who underwent unilateral or bilateral percutaneous pedicle screw fixation after MIS TLIF for 1-segment lumbar degenerative disc disease. Twenty-six patients were assigned to a unilateral percutaneous pedicle screw fixation group and 27 patients were assigned to a bilateral percutaneous pedicle screw fixation group. Operative time, blood loss, clinical outcomes (that is, Oswestry Disability Index [ODI] and visual analog scale [VAS] scores), complication rates, and fusion rates were assessed using CT scanning 2 years after surgical treatment.nnnRESULTSnThe 2 groups were similar in age, sex, preoperative diagnosis, and operated level, and they did not differ significantly in the length of follow-up (27.5 [Group 1] vs 28.9 [Group 2] months) or clinical results. Both groups showed substantial improvements in VAS and ODI scores 2 years after surgical treatment. The groups differed significantly in operative time (unilateral 84.2 minutes; bilateral 137.6 minutes), blood loss (unilateral 92.7 ml; bilateral, 232.0 ml), fusion rate (unilateral 84.6%; bilateral 96.3%), and postoperative scoliotic change (unilateral 23.1%; bilateral 3.7%).nnnCONCLUSIONSnUnilateral and bilateral screw fixation after MIS TLIF produced similar clinical results. Although perioperative results were better with unilateral screw fixation, the long-term results were better with bilateral screw fixation, suggesting bilateral screw fixation is a better choice after MIS TLIF.

New prognostic factors for adjacent-segment degeneration after one-stage 360 degrees fixation for spondylolytic spondylolisthesis: special reference to the usefulness of pelvic incidence angle.

Object. The purpose of this study was to evaluate the correlation between adjacent-segment degeneration (ASD) and pelvic parameters in the patients with spondylolytic spondylolisthesis. Sagittal balance is the most important risk and prognostic factor in the development of ASD. The pelvic incidence angle (PIA) is an important anatomical parameter in determining the sagittal curvature of the spine and in the individual variability of the sacral slope and the lordotic curve. Thus, the authors evaluated the relationship between the pelvic parameters and the ASD. Methods. Among 132 patients with spondylolytic spondylolisthesis who underwent surgery at their institution, the authors selected patients in whom a one-stage, single-level, 360° fixation procedure was performed for Grade I spondylolisthesis and who underwent follow-up for more than 1 year. Parameters in 34 patients satisfied these conditions. Of the 34 patients, seven had ASD (Group 1) and 27 patients did not have ASD (Group 2). The investigators measured degree of spondylolisthesis, lordotic angle, sacral slope angle (SSA), pelvic tilt angle (PTA), PIA, and additional parameters pre-and postoperatively. The radiographic data were reviewed retrospectively. Results. The population consisted of nine men and 25 women whose mean age was 48.9 ± 9 years (± standard deviation) (range 28-65 years). Seven patients developed ASD after undergoing fusion. Of all the parameters, pre-and postoperative degree of spondylolisthesis, segmental lordosis, lordotic angle, SSA, preoperative PTA, and preoperative PIA did not differ significantly between the two groups; only postoperative PTA and PIA were significantly different. Conclusions. The development of ASD is closely related to postoperative PIA and PTA, not preoperative PIA and PTA. The measurement of postoperative PIA can be used as a new indirect method to predict the ASD.OBJECTnThe purpose of this study was to evaluate the correlation between adjacent-segment degeneration (ASD) and pelvic parameters in the patients with spondylolytic spondylolisthesis. Sagittal balance is the most important risk and prognostic factor in the development of ASD. The pelvic incidence angle (PIA) is an important anatomical parameter in determining the sagittal curvature of the spine and in the individual variability of the sacral slope and the lordotic curve. Thus, the authors evaluated the relationship between the pelvic parameters and the ASD. Methods. Among 132 patients with spondylolytic spondylolisthesis who underwent surgery at their institution, the authors selected patients in whom a one-stage, single-level, 360 degrees fixation procedure was performed for Grade I spondylolisthesis and who underwent follow-up for more than 1 year. Parameters in 34 patients satisfied these conditions. Of the 34 patients, seven had ASD (Group 1) and 27 patients did not have ASD (Group 2). The investigators measured degree of spondylolisthesis, lordotic angle, sacral slope angle (SSA), pelvic tilt angle (PTA), PIA, and additional parameters pre-and postoperatively. The radiographic data were reviewed retrospectively. Results. The population consisted of nine men and 25 women whose mean age was 48.9 +/- 9 years (+/- standard deviation) (range 28-65 years). Seven patients developed ASD after undergoing fusion. Of all the parameters, pre- and postoperative degree of spondylolisthesis, segmental lordosis, lordotic angle, SSA, preoperative PTA, and preoperative PIA did not differ significantly between the two groups; only postoperative PTA and PIA were significantly different. Conclusions. The development of ASD is closely related to postoperative PIA and PTA, not preoperative PIA and PTA. The measurement of postoperative PIA can be used as a new indirect method to predict the ASD.

The relevance of intramedullary high signal intensity and gadolinium (Gd-DTPA) enhancement to the clinical outcome in cervical compressive myelopathy

PurposeWe prospectively investigated whether high intramedullary SI and contrast [gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA)] enhancement in magnetic resonance imaging (MRI) are associated with postoperative prognosis in cervical compressive myelopathy (CCM) patients.MethodsSeventy-four patients with ventral cord compression at one or two levels underwent anterior cervical discectomy and fusion (ACDF) for CCM between March 2006 and June 2009. The mean follow-up period was 39.7xa0months (range, 12.7–55.7xa0months). The cervical cord compression ratio and clinical outcomes were measured using Japanese Orthopedic Association (JOA) scores for cervical myelopathy. Patients were classified into three groups based on the SI change in T2WI, T1-weighted images (T1WI), and contrast (Gd-DTPA) enhancement.ResultsThe mean preoperative and postoperative JOA scores were 10.5xa0±xa02.9 and 15.0xa0±xa02.1 (Pxa0<xa00.05), respectively. The mean recovery ratio of the JOA score was 70.9xa0±xa020.2%. There were statistically significant differences in postoperative JOA and recovery ratio among three groups. However, post-surgical neurological outcomes were not associated with age, symptom duration, preoperative JOA, and cord compression.Conclusions We found that intramedullary SI change is a poor prognostic factor and the intramedullary contrast (Gd-DTPA) enhancement on preoperative MRI should be viewed as the worst predictor of surgical outcomes in cervical myelopathy. Contrast (Gd-DTPA) enhancement and postoperative MRI are useful for identifying the prognosis of patients with poor neurological recovery.

What are the associative factors of adjacent segment degeneration after anterior cervical spine surgery? Comparative study between anterior cervical fusion and arthroplasty with 5-year follow-up MRI and CT

PurposeIt is well known that arthrodesis is associated with adjacent segment degeneration (ASD). However, previous studies were performed with simple radiography or CT. MRI is most sensitive in assessing the degenerative change of a disc, and this is the first study about ASD by radiography, CT and MRI. We sought to factors related to ASD at cervical spine by an MRI and CT, after anterior cervical spine surgery.Materials and methodsThis is a retrospective cross-sectional study of cervical disc herniation. Patients of cervical disc herniation with only radiculopathy were treated with either arthroplasty (22 patients) or ACDF with cage alone (21 patients). These patients were required to undergo MRI, CT and radiography preoperatively, as well as radiography follow-up for 3xa0months and 1xa0year, and we conducted a cross-sectional study by MRI, CT and radiography including clinical evaluations 5xa0years after. Clinical outcomes were assessed using VAS and NDI. The fusion rate and ASD rate, and radiologic parameters (cervical lordosis, operated segmental height, C2-7 ROM, operated segmental ROM, upper segmental ROM and lower segmental ROM) were measured.ResultsThe study groups were demographically similar, and substantial improvements in VAS (for arm) and NDI (for neck) scores were noted, and there were no significant differences between groups. Fusion rates were 95.2xa0% in the fusion group and 4.5xa0% in the arthroplasty group. ASD rates of the fusion and arthroplasty groups were 42.9 and 50xa0%, respectively. Among the radiologic parameters, operated segmental height and operated segmental ROM significantly decreased, while the upper segmental ROM significantly increased in the fusion group. In a comparative study between patients with ASD and without ASD, the clinical results were found to be similar, although preexisting ASD and other segment degeneration were significantly higher in the ASD group. C2-7 ROM was significantly decreased in ASD group, and other radiologic parameters have no significant differences between groups.ConclusionThe ASD rate of 46.5xa0% after ACDF or arthroplasty, and arthroplasty did not significantly lower the rate of ASD. ASD occurred in patients who had preexisting ASD and in patients who also had other segment degeneration. ASD may be associated with a natural history of cervical spondylosis rather than arthrodesis.

Comparative expression of matrix-associated genes and inflammatory cytokines-associated genes according to disc degeneration: analysis of living human nucleus pulposus.

Study Design The 2 groups of living human nucleus pulposus were prospectively compared according to disc degeneration. Objectives This study was conducted to investigate the expressions of various genes associated with matrix synthesis and expressions of inflammatory cytokines-associated genes according to degrees of disc degeneration in human discs. Summary of Background Data Degenerated discs were obtained from 18 patients who underwent discectomy for lumbar disc herniation. Disc degeneration was graded by T2-weighted magnetic resonance imaging using Pfirrmanns grading system. Discs were allocated to 2 groups: group I (9 patients)—mildly degenerated discs (grades II and III) and group II (9 patients)—severely degenerated discs (grades IV and V). Methods Cells from the nucleus pulposus were isolated and then cultured as monolayers. The mRNA expressions of aggrecan, type II collagen, Sox9, type I collagen, alkaline phosphatase, osteocalcin, tumor necrosis factor-&agr;, and interleukin-1&bgr; in the 2 groups were compared by real-time polymerase chain reaction, and production of matrix-associate proteins (aggrecan, type II collagen, Sox9, type I collagen, alkaline phosphatase, and osteocalcin) were compared by Western blotting. Results mRNA expressions in group I were upregulated versus group II to the following extents: 1.83 times for aggrecan, 1.82 times for type II collagen, 1.80 times for Sox9, 1.41 times for type I collagen, 1.38 times for alkaline phosphatase, and 1.80 times for osteocalcin. Furthermore, Western blotting showed that aggrecan, type II collagen, Sox9, type I collagen, alkaline phosphatase, and osteocalcin were higher in group I. However, the mRNA levels of tumor necrosis factor-&agr; and interleukin-1&bgr; were 1.26 and 1.11-fold, respectively, upregulated in group II. Conclusions Mildly degenerated discs showed greater matrix, chondrogenic, and osteoblastic gene expressions than severely degenerated discs, indicating that the ability to produce matrix-associated proteins is greater for cells in mildly degenerated than in severely degenerated discs. However, inflammatory cytokine genes associated with disc degeneration were expressed at higher levels in the severely degenerated group. This study shows that a reduction in matrix synthesis and an increase of inflammatory cytokine levels occurs during disc degeneration at the same time.

A comparison of three cell types as potential candidates for intervertebral disc therapy: annulus fibrosus cells, chondrocytes, and bone marrow derived cells.

OBJECTIVESnCandidate cell types for disc cell transplantation therapy include anulus fibrosus (AF) cells, chondrocytes, and bone marrow derived cells (BMDCs). We compared the disc matrix production in these three types of cells, before and after stimulation with rhBMP-2. There is no study extant that compares these three cell types to determine the best candidate for the disc cell therapy.nnnMETHODSnAF cells, chondrocytes, and BMDCs (iliac crest and femur) were isolated and grown in monolayer. They were treated for 3 days with rhBMP-2. After 3 days, proteoglycan (sGAG) content in the media was quantified. The results were normalized by cell numbers. The mRNA expression of aggrecan, type I collagen, and type II collagen was measured using real-time PCR. Each cell type was also cultured in chamber slides and immunostained for aggrecan, type I collagen, and type II collagen after 3 days of treatment with rhBMP-2.nnnRESULTSn(1) Without rhBMP-2 the chondrocytes produced more proteoglycan (sGAG) as compared to the other two cell types (AF cells and BMDCs). After stimulation with rhBMP-2 the chondrocytes produce even more proteoglycan than the other two cell types. (2) As compared to the other two cell types, in terms of mRNA expression, the chondrocytes expressed more aggrecan, type I collagen, and type II collagen before stimulation with rhBMP-2. After rhBMP-2 stimulation, the chondrocytes expressed even more aggrecan, type I collagen, and type II collagen in proportion to the concentration of rhBMP-2. For the BMDCs there were no changes in type I and II collagen. (3) rhBMP-2 stimulation produced increases in the protein levels of aggrecan, type I and II collagen in all three types of cells.nnnCONCLUSIONSnOn balance, according to these results, it would seem that chondrocytes are the best candidate for the disc cell therapy.

Can TGF-β1 and rhBMP-2 act in synergy to transform bone marrow stem cells to discogenic-type cells?

IntroductionThe recombinant human bone morphogenic protein-2 (rhBMP-2) is known to increase the proteoglycan production and chondrogenic gene expression in the disc cells. The transforming growth factor-beta 1 (TGF-β1) can transform the bone marrow stem cells (BMDCs) into the disc-like cells.Materials and methodsWe carried out an experiment to determine if TGF-β1 and rhBMP-2 can act in synergy on BMDCs by increasing the production of sulfated-glycosaminoglycan (sGAG) and affecting the mRNA expression of aggrecan, type I collagen, and type II collagen. The BMDCs were isolated from the iliac crest and femur of a New Zealand white rabbit (1xa0year). The BMDCs were culured in monolayer and treated for 6xa0days with TGF-β1 10xa0ng/ml (group 1), rhBMP-2 200xa0ng/ml (group 2), and both TGF-β1 10xa0ng/ml and rhBMP-2 200xa0ng/ml (group 3: the combined group) in Dulbecco’s modified Eagle medium/F-12 with 1% fetal bovine serum. After 6xa0days, the sGAG content in the media was quantified using 1,9-dimethylmethylene blue staining and the mRNA expression of aggrecan, type I collagen, type II collagen, Sox-9, BMP-2, and BMP-7 were measured with the real-time PCR. The same BMDCs were also cultured in the chamber slide at 3u2009×u2009104 cells/chamber. After 6xa0days treatment, the treated cells were immunofluorescence stained with aggrecan, type I collagen, type II collagen, anti-BMP-2, anti-BMP-7 antibodies. After that, we compared the number of positive immunofluorescence stained cells with fluorescence microscope. The sGAG production and mRNA expression for each group were normalized against the same parameters for a non-treatment group.Results and discussionThe sGAG production was increased 1.15*, 1.34*, and 1.45* times in the TGF-β1 10xa0ng/ml group, the rhBMP-2 200xa0ng/ml group, and the combined group respectively. The mRNA expression of aggrecan was increased 1.28, 3.42*, and 5.34* times, the mRNA expression of type I collagen was increased 0.86, 1.09, 1.17 times, the mRNA expression of type II collagen was increased 3.58*, 3.77*, and 10.78* times, the mRNA expression of Sox-9 was increased 1.29, 2.45, 2.75* times, the mRNA expression of BMP-2 was increased 1.14, 2.07, 4.43* times, and the mRNA expression of BMP-7 was increased 1.16, 1.49, 1.97* times, respectively for each group (* indicates pu2009<u20090.05). On the immunofluorescence staining of antibodies, the average positively immunofluorescence stained cells number for aggrecan were 4.2, 15.8*, 10*, and 22* according to the non-treatment group, TGF-β1 10xa0ng/ml group, rhBMP-2 200xa0ng/ml group, and the combined group respectively. The average positively immunofluorescence stained cells number for type I collagen were 7, 14.2*, 9.2*, 17.4* and the average positively immunofluorescence stained cells number for type II collagen were 8.5, 28.25*, 20.25*, 42.25* and the average positively immunofluorescence stained cells number for anti-BMP-2 were 5, 16.75*, 8.75*, 27.25* and the average positively immunofluorescence stained cells number for anti-BMP-7 were 3.25, 7.5*, 8.75*, 15.25* (* indicates pu2009<u20090.05).ConclusionsBoth TGF-β1 and rhBMP-2 alone, can increase proteoglycan production in the BMDCs. However, if they were used in combination, there is a synergistic effect. Similarly, the mRNA expressions of both aggrecan, type II collagen, Sox-9, BMP-2, and BMP-7 except for type I collagen were increased significantly when TGF-β1 and rhBMP-2 were combined. The positive immunofluorescence stained cell numbers for aggrecan, type I, II collagen, BMP-2 and BMP-7 were also increased after each TGF-β1 and rhBMP-2 treatment, and also more increased significantly in the aggrecan, type I, II collagen, BMP-2, and 7 when they were used jointly.

Minimally Invasive Transforaminal Lumbar Interbody Fusion for Spondylolisthesis: Comparison Between Isthmic and Degenerative Spondylolisthesis

INTRODUCTIONnMinimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a common surgical option for degenerative spondylolisthesis (DS). However, its effectiveness for isthmic spondylolisthesis (IS) is still controversial. No current studies have directly compared perioperative and postoperative results including various radiological parameters between IS and DS after MIS TLIF.nnnPURPOSEnThe purpose of this study is to compare the clinical and radiological results between isthmic and degenerative spondylolisthesis after MIS TLIF.nnnMETHODSnThis is a retrospective study of 41 patients who underwent MIS TLIF for single-segment, grade 1 or 2 IS (n = 18) and DS (n = 23). The same surgical techniques and procedure were applied to both groups. Perioperative outcomes (operation time, blood loss, hospital stay, complications); clinical outcomes (visual analog scale [VAS], Oswestry Disability Index [ODI]); radiological parameters (disk height, degree of spondylolisthesis, slip angle, lumbar lordosis, segmental lordosis, sacropelvic parameters: pelvic incidence, sacral slope, pelvic tile); and fusion rates using computed tomography scanning were compared between groups at 1 year postoperatively.nnnRESULTSnThere were no significantly different perioperative results between groups. Mean VAS and ODI scores improved significantly postoperatively in both groups but were not significantly different between groups at each follow-up point. Radiological parameters were not significantly different between groups except disk height and degree of spondylolisthesis. The disk heights were increased postoperatively (IS: 6.79-9.22 mm; DS: 8.18-8.97 mm) in both groups, and there were significant differences preoperatively. In addition, disk height restoration was greater for IS than DS (2.43 mm vs. 0.79 mm, P = 0.01). However, postoperative disk heights were not significantly different between groups. The degree of spondylolisthesis was significantly different between groups both preoperatively (16.77% vs. 11.33%, P < 0.01) and postoperatively (9.79% vs. 3.78%, P < 0.01). However, slip reduction was no different between groups (6.97 vs. 7.56%, P = 0.74). Fusion rates were not significantly different between groups.nnnCONCLUSIONSnMIS TLIF resulted in similar clinical outcomes when used to treat both isthmic and degenerative spondylolisthesis. Although disk height restoration was more effective for IS than DS, other radiological parameters including fusion rate were no different between groups. For both isthmic and degenerative spondylolisthesis, MIS TLIF can be a safe and effective surgical option.